LOS ANGELES, California (CNN) -- Jay Leno will hand over the reins of NBC's "The Tonight Show" to "Late Night" host Conan O'Brien -- but not until 2009, the network announced Monday.

"In 2009, I'll be 59 years old and will have had this dream job for 17 years," Leno said in NBC's written statement. "I felt that the timing was right to plan for my successor and there is no one more qualified than Conan."

"Plus, I promised Mavis (his wife) I would take her out for dinner before I turned 60," Leno said.

O'Brien, 41, has signed a contract to stay in his current job at 12:30 a.m. ET for the next five years and then take over the top-rated late-night show when Leno retires.

"Jay Leno and Conan O'Brien continue to be the most successful combination in all of late night," said NBC senior vice president Rick Ludwin. "We have locked in the future ... for years to come."

It's not clear just how long O'Brien is "locked in." NBC would not say how long his new contract lasts, nor how much he and Leno are to be paid.

The early announcement avoids a replay of the early 1990s, when the retirement of veteran host Johnny Carson touched off a behind-the-scenes battle between Leno and then- "Late Night" host David Letterman over who would be Carson's successor.

That feud ended with Letterman going to CBS to compete head-to-head with Leno. Letterman took an early lead in the ratings, but Leno has been consistently ahead for the last nine years.

O'Brien, in the statement, called "The Tonight Show" "one of the great franchises in television" and said he is "thrilled to get this opportunity."

"I am thankful to everyone at NBC -- which has been my home for the last 11 years -- and I am particularly grateful to Jay for all the generous support and kindness he has always shown me," he said.

The announcement leaves an upcoming vacancy in the 12:30 a.m. time slot, a position that catapulted both Letterman and O'Brien onto TV's lucrative A-list.

Leno, a stand-up comic, was Carson's guest host before taking over full-time. O'Brien was a writer for "Saturday Night Live" and "The Simpsons" before landing the "Late Night" job in 1993.